After uploaded and moved to a folder for organizational purposes, some GIF files will retain their normal quality and will have a small camera icon at the top of it's thumbnail, while others lose this icon, and will not animate when dragged onto a scene. These all still work (and still have the camera icon) when dragged onto a scene from "Recent Uploads". Deleting them from the folder and adding them back has no effect. Reloading the scene/ game also has no effect. My guess is that there is a threshold based on file size that's causing the issue, as only the smallest of GIFs seem to retain their animation while in a folder.